Spinning artificial silk



Patented June 23, 1936 UNITED STATES PATENT OFFICE SPINNING ARTIFICIALSILK No Drawing. Application February 26, 1931, Serial No. 518,598. InGermany March 6,

Our present invention relates to a new process of manufacturingartificial fibers from a viscose solution and more particularly to a newsetting bath used in the manufacture of artificial products fromviscose.

Viscose silk of high tenacity has already been made by spinning viscoseinto precipitating baths containing at least 45% of sulfuric acidmonohydrate'.

According to this invention it is possible to obtain threads having astrength of over 200 grams per 100 deniers by making use of suchprecipitating baths as contain considerably smaller amounts of sulfuricacid monohydrate. The proposed aim may be reached by spinning viscose,produced from unripened or only slightly ripened alkali cellulose, intobaths containing besides 10 to 30% of sulfuric acid monohydrate morethan 30% of a bisulfate, and stretching the threads during their processof manufacture. It is advantageous to almost saturate the acid solutionswith bisulfate. The best action is obtained with ammonium bisulfatewhich dissolves particularly well in acid baths. Sodium bisulfate andother easily soluble bisulfates or mixtures of different bisulfates may,however, likewise be used. Under the term slightly ripened alkalicellulose we wish to be understood alkali cellulose which has ripenedfor a shorter time than that considered to be normal, that is to sayless than 96 hours at a temperature of 18 C.

It is a known fact that baths which contain a bisulfate besides freesulfuric acid, do not give satisfactory results (cf. German Patent No.287,-

955, page 1, lines 33-37) Hence it is surprising that baths of the saidcomposition not only allow of well spinning, but even yield a silk of aparticularly high strength, if the baths-contain besides sulfuric acidconsiderable quantities of bisulfate and if the thread is stretchedwhile being spun. The threads may be stretched either by stationary rodsor by eyes or by other mechanical means, or they may be stretched byenhancing the speed of spinning or by the current of the spinning bathor by a prolonged passage through the bath.

Although viscoses from alkali cellulose ripened for several days stillyield strengths of up to 2 grams per denier, especially when they have ahigher content of cellulose, viscoses from unripened alkali cellulosewill always give higher strengths. stretched when particularly highlysulfided xanthogenates are used. It is advantageous to prevent anydegradation of the cellulose during The thread can more easily be,

13 Claims. (CI. 1854) the diiferent steps of manufacture; this may, forinstance, be done by completely excluding oxygen or by similar measures.Threads from cellulose which has been degraded to as small an extent aspossible have, as a rule, higher strengths or in the w. An unripenedalkali cellulose, sulfided with 32 per cent by weight of carbondisulfide (calculated upon cellulose) is dissolved to form a viscosecontaining 6% of cellulose and 6.5% of alkali.

b. A viscose is made according to a but the alkali cellulose is sulfidedwith per cent by weight of carbon disulfide.

The viscose prepared according to a or b is spun into a precipitatingbath containing 28 per cent of. free sulfuric acid and being nearly saturated with ammonium bisulfate and sodium bisulfate, through a spinningnozzle provided with 700 perforations, the width of each perforationbeing 0.1 mm. The viscose pump is thus adjusted to deliver about 9 com.of the viscose solution per minute. The length of passage of the threadsin the bath may be 25 cm., while the length of passage in the air may becm. The speed of draught is 30 in. per minute. Under these con ditions,a thread is obtainable having a total titer of deniers. The spinningtemperature of the bath is 40 C. After leaving the precipitating bath,the thread is stretched over 3 eyes spaced apart in the form of atriangle.

The strength of the threads obtained exceeds 350 grams per 100 denierswith an elongation of 6 to '7 per cent.

Example 2 In a xanthogenate machine, cellulose ls introduced into acaustic soda solution of 19% strength. After the swelling of thecellulose, the mass is kneaded at 10 C. until it has become homogeneous.The mass is sulfided with 50% of carbon disulfide for 3 to 4 hours at'atemperature of 26 C.; the sulfided product is dissolved at 15 C. in acaustic soda solution of 1% strength to form a viscose containing 5% ofcellulose and 4% of alkali.

The viscose is spun into a bath consisting of 28% of free sulfuric acid,32% of ammonium bisulfate, 8% of sodium bisulfate and 32% of water whilestrongly stretching the freshly precipitated threads. During spinningthe following working conditions are to be maintained:

The temperature of the bath is 37 C. The spinning nozzle has 120perforations, the width of each perforation being 0.09 mm. The speed ofdraught is 30 m. per minute. The length of passage of the thread in thebath is 50 cm. and that through the air, likewise, 50 cm. The viscosepump is thus adjusted to deliver 7.2 ccm. of the spinning solution perminute.

The threads obtained have a total titer of 120 deniers, a strength ofover 300 grams per 100 deniers and an elongation of 7 to 8%.

E :rample 3 There is spun a viscose from alkali cellulose which hasripened for a short time, for instance, for 12 hours, containing 9% ofcellulose and 8% of alkali and having a viscosity of about 150 secondsdetermined in the ball viscosimeter (that is to say, a steel ball of 0.1gram needs 150 seconds to pass through a tube of 18 mm. width and 20 cm.length filled with the viscose to be determined). The spinning bathconsists of 24% of sulfuric acid, 35% of ammonium bisulfate, 12% ofsodium bisulfate and 29% of water. The spinning temperature is 40 C. Aspinning nozzle is used having 120' perforations, each perforationhaving a diameter of 0.09 mm. The length of passage of the thread in thesetting bath is 25 cm. and that through the air 50 cm. The viscose pumpdelivers about 4 cm, per minute. After leaving the bath, the threads arestretched in the usual manner. They have a total titer of 120 deniers, astrength of 330, and an elongation of 6 to 7%.

Example 4 The spinning bath consists of a solution of 39% of ammoniumbisulfate, 11% of sodium bisulfate, 18 per cent of sulfuric acidmonohydrate and 32 per cent of water. Into this bath a viscose accordingto Example 1 a is spun at 40 C., through a spinning nozzle provided with120 perforations, each perforation having a diameter of 0.07 mm. whilestretching the freshly precipitated threads. The speed of draught is 30m. per minute, the length of passage through the bath is 25 cm. and thatthrough the air cm. The viscose pump is thus adjusted to deliver 6 com.of the spinning solution per minute.

The threads obtained have a total titer of 120 deniers, a strength ofover 250 per deniers and an elongation of 6 to 7%.

.Escample 5 A viscose according to Example 1 a is spun at 45 C. underthe same conditions as mentioned in the foregoing example, into aprecipitating bath consisting of 12% of sulfuric acid monohydrate, 48%of ammonium bisulfate, 14% of sodium bisulfate and 26% of water, whilestrongly stretching.

The threads obtained have a strength of 230 per 100 deniers and anelongation of 8.3%.

Our invention is not limited to the foregoing examples or to thespecific details given therein.

The passages through the bath and through the air may be varied incertain limits. The first named may be, for instance, 10 to 50 cm. oreven longer and the latter may vary between 50 and 200 cm. As spinningnozzles there may be used, for instance, nozzles /0.05 (120 perforationsof an individual diameter of 0.05 mm.) or nozzles 120/0.09, TOO/0.10 or1000/0.10. The viscose pump may be adjusted with each spinning nozzle todeliver the quantity of spinning solution required for the desired totaltiter.

The same holds true with respect to the correct composition of thesetting bath or to the temperature of the latter. Preferably atemperature between 30 to 50 C. is to be maintained during the spinningoperation. However, this temperature likewise may be varied.

Viscose solutions having a higher or smaller content of cellulose thanthose indicated in the examples, may be used.

If necessary, a few simple comparative experiments should be made inorder to determine the best working conditions, the most suitablecomposition and the best temperature of the setting bath to be used witha particular viscose solution prepared from an unripened or slightlyripened alkali cellulose.

As indicated above, other assistants well known in the manufacture ofartificial silk, may be added either to the spinning solution or to theprecipitating bath.

The processes of after-treating the fibers, such as washing,desulfurizing, bleaching and so on, are carried out as usual. Inconsideration of the acid and salt concentration adhering to the spunfiber we prefer, however, to join the washing immediately to thespinning operation.

All the various modifications mentioned above and changes in detail areconsidered to be within the spirit of our invention and the scope of thefollowing claims.

What we claim is:

l. The process of manufacturing artificial fibers of high tenacity,which comprises causing a viscose prepared from an unripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 10 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of a bisulfate soluble in the acid bath, andstretching the freshly precipitated threads.

2. The process of manufacturing artificial fibers of high tenacity,which comprises causing a viscose prepared from an unripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 10 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of ammonium bisulfate, and stretching the freshlyprecipitated threads.

3. The process of manufacturing artificial fibers of high tenacity,which comprises causing a viscose prepared from an unripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 10 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of ammonium bisulfate and in addition an alkali metalbisulfate, and stretching the freshly precipitated threads.

4. The process of manufacturing artificial fibers of high tenacity whichcomprises causing a viscose prepared from an unripened alkali celluloseto pass through suitably formed openings into a coagulation bathcontaining 24 to 30 per cent of sulfuric acid monohydrate and at leasting the freshly precipitated threads.

5. The process of manufacturing artificial fibers of high tenacity whichcomprises causing a viscose prepared from an unripened alkali celluloseto pass through suitably formed openings into a coagulation bathcontaining 24 to 30 per cent of sulfuric acid monohydrate and at least30 per cent of ammonium bisulfate and in addition an alkali metalbisulfate, and stretching the freshly precipitated threads.

6. The process of manufacturing artificial fibers of high tenacity whichcomprises causing a viscose prepared from slightly ripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing to 30 per cent of sulfuric acid monohydrate and at least30 per cent of a bisulfate soluble in the acid bath, and stretching thefreshly precipitated threads.

7. The process of manufacturing artificial fibers of high tenacity whichcomprises causing a viscose prepared from slightly ripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 10 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of ammonium bisulfate, and stretching the freshlyprecipitated threads.

8. The process of manufacturing artificial fibers of high tenacity whichcomprises causing a viscose prepared from slightly ripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 10 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of ammonium bisulfate and in addition an alkali metalbisulfate, and stretching the freshly precipitated threads.

9. The process of manufacturing artificial fibers of high tenacity whichcomprises causing a viscose prepared from slightly ripened alkalicellulose to pass through suitably formed openings into a coagulationbath containing 24 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of ammonium bisulfate, and stretching the freshlyprecipitated threads.

10. The process of manufacturing artifical fibers of high tenacity whichcomprises causing a viscose prepared from slightly ripened alkalicellulose to pass through suitably formed openings into a coagulationbath containing 24 to 30 per cent of sulfuric acid monohydrate and atleast 30 per cent of ammonium bisulfate and in addition an alkali metalbisulfate, and stretching the freshly precipitated threads.

11. The process of manufacturing artificial fibers of high tenacitywhich comprises causing a viscose prepared from unripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 28% of free sulfuric acid and being nearly saturatedwith ammonium bisulfate and sodium bisulfate, and stretching the freshlyprecipitated threads.

12. The process of manufacturing artificial fibers of high tenacitywhich comprises causing a viscose prepared from alkali cellulose whichhas ripened for twelve hours to pass through suitably formed openingsinto a coagulating bath containing 24% of sulfuric acid, 35% of ammoniumbisulfate, 12% of sodium bisulfate and 29% of water, and stretching thefreshly precipitated threads.

13. The process of manufacturing artificial fibers of high tenacitywhich comprises causing a viscose prepared from unripened alkalicellulose to pass through suitably formed openings into a coagulatingbath containing 12% of sulfuric acid, 48% of ammonium bisulfate, 14% ofsodium bisulfate and 26% of water, and stretching the freshlyprecipitated threads.

JOHANNES KLEINE. HUGO PFANNENSTIEL. WERNER MAII'I'HAES.

